I have to say some of my rooms can get kinda bizzare and strange (i.e. super doungeon) but I have to say, this new apaartment I'm making has some of the coolest rooms ever. It has 2 penthouse suites, 2 suites, 16 rooms (Not using them all but hey) and to cut down on room cost, there is a communal kitchen and rec room, but this is not the oddest feture, the odest feture is the elevator service rooms in the front of the building, and needless to say I'm looking for utility room objects too.

I don't know what would qualify as weird ... but umm. I think my weirdest room was the bedroom that I made just for my dog

I also had a room for animals only - there was a family with three cats, and I made a little room especially for them.
In some classy rich houses, I sometimes make roms for games (pool, cards, chess, darts) so that the family and their guests can have fun there.
I also had party rooms.
In my apartment buildings, the ground floor is often occupied by a gym, a laundry, a communal restroom, and, if the space allows, indoor swimmingpool. But I don't think it is wierd.

The 'magic' room I have for my witches. It has their cauldrons and spellbooks, with a secret bookcase door (although I just use magivestium most of the time).

How about a HUGE one-room house made with Numenor`s WallWindow set, transparent floor-tiles for roofing, and bare terrain for the floor? It takes up the front-left quarter of the biggest-sized lot it is on. Behind it is a similar room made with greenhouse walls where the PlantSims who live there grow food. In the front-right corner of the lot is another WallWindow room where they are building a swimming pool, and I believe that the remaining quarter has a similar uncomitted room. All four rooms are seperate construction, i.e., four one-room buildings on the lot, with narrow corridors between. The male PlantSim is also a Vampyre, so he spends a LOT of daytime in the bathtub. They also run a home-business there. Oddly enough, I`m scheduled to play them after work today.

I also have a small windowless room for a Vampyre PlantSim Witch who lives on another lot; a former bedroom, I installed a Garden Catalog sunlamp, a shower, her spell-book and cauldren, and a computer, and she blogs about her Hobby interests [to keep her maximized in them], takes showers as needed, calls people on her cell-phone when her Love gets low, and spends the rest of her copius free time making reagents. She is my first --and so far only-- Witch to make maximum Magic Ability [though someone else --who is neither PlantSim nor Vampyre-- is my first --and so far only-- Player Witch to attain maximum Good Witch alignment]. At night, she runs an OfB store on another lot.

I do not know if this counts as a room, but I made a public toilet with OFB once. The men's room had a bar message table weight bench an a arcade game. The women's room had a hot tub, stereo, ballet bar, wardrobe etc. It was the best business I have ever made, it made money hand over fist, charging 1 simolian an hour, the price I figured a coin operated stall would charge in real life.

I used to make huge rec rooms with every activity. Pool table, disco, couch, bookcase, piano, bar, a few hot tubs, and pretty much everything.
I also used to make "beach rooms" at beaches with stuff like, well, all of the above. Needless to say nobody every went into the water.
Also, call me weird, but many of my self-made dorms have kitchens, bathrooms, etc inside them and since you can't make apartments at college I use them as apartments and there is no cafeteria lady.

I just built a house where each room had to be either two blocks larger or two blocks smaller than the room it connected to--so I wound up with this bizarre sprawling thing with lots of rooms. So I have rooms for practically any activity -- art rooms, music rooms, tinkering rooms, indoor pool--lots of fun stuff.

I was getting ready to build a house in my last game where every thing fit on a 3X2 rug. More than one of course, I was planning to make an entire house accordingly. Every room would be 3x2.